Method of radiant heat sealing of a balloon onto a catheter employing tinted shrink tubing

ABSTRACT

A thermoplastic member such as a length of tubing for forming a catheter balloon is positioned on the thermoplastic shaft of a medical device. A length of shrink tubing is placed over each end of the balloon tubing and adjoins a portion of the shaft. Each length of shrink tubing may then be preshrunk to maintain its position. The shaft, balloon tubing, and shrink tubing are then inserted in an apparatus capable of supplying radiant heat in a narrow annular band. The apparatus automatically positions each portion of the shaft and balloon tubing covered by shrink tubing at a location at which it will intercept the narrow annular band of radiant heat. Radiant heat is supplied by the apparatus to cause further shrinkage of the shrink tubing and to seal the balloon tubing onto the shaft. The shrink tubing may be removed to complete the assembly of a balloon catheter. It is preferred that the shrink tubing be tinted so as to enhance the seal formed between the balloon tubing and the shaft.

BACKGROUND AND DESCRIPTION OF THE INVENTION

The present invention relates generally to providing seals along shaftsof medical devices by means of radiant energy and is especially suitablefor seals of catheter balloons onto catheter shafts. Various aspects ofthe invention include a radiant energy sealing apparatus as a means forrapidly forming finished medical device products while precisely andautomatically aligning the energy emission at desired locations on theproduct, a method of manufacturing these medical devices through the useof shrink tubing, and a particularly advantageous shrink means for usein conjunction with the apparatus and the method.

Balloon catheters and other medical devices having overlying cylindricalmembers must develop smooth and secure annular seals or bonds betweendifferent assembly parts. In the case of balloon catheters, the balloonis initially an assembly part in the form of an overlying cylindricalmember that has to be very securely sealed onto the cylindrical shaft ofthe catheter near its head. Upon completion of the catheter, the balloonis inflatable so as to make possible, in the case of a Foley catheterfor example, retention of the catheter head within the bladder of apatient whereby body fluids can be drained therefrom through the urethravia a lumen through the catheter shaft. Seals for this purpose should beaccurately formed, should be as smoothly tapered as possible, and shouldpresent very low adulteration risks in order to minimize the chances ofpatient trauma and urinary tract irritation.

Long used in manufacturing such catheters and the like has been naturalrubber latex which is low in cost and has the assembly advantage thatthe balloon and shaft can be molded in one piece, but which material hascome under criticism because of the belief that when devices madetherefrom are left within the patient for longer than a day or so,reactions develop with tissue adjacent the catheter that can lead toconsiderable patient discomfort.

Manufacturing such medical devices from materials other than naturalrubber latex or the like generally necessitates a two-piece assembly ofthe balloon cylinder to the catheter shaft, which assembly can becarried out by such general approaches as bonding the balloon to theshaft with an adhesive, by heat sealing a thermoplastic balloon to athermoplastic shaft, or by combining adhesives with heat sealing.Adhesives are used for silicone rubber devices but they are usually bestavoided because of the additional handling steps and time needed duringmanufacture and because of potential adulteration risks associatedgenerally with the use of adhesives in medical equipment. Radiofrequency heating is generally unsatisfactory because of the need tocontact the parts being sealed which deforms the surface and does notallow ready transfer of heat to the interface between the parts, andbecause of non-uniformity of surface and seal. The use of radiant energyand thermoplastic materials for medical devices to be heat sealed arementioned in U.S. Patent Application Ser. No. 853,738, filed Nov. 21,1977, U.S. Pat. Nos. 4,154,244, and 900,965, filed Apr. 28, 1978, U.S.Pat. No. 4,198,983 , the disclosures thereof being incorporated byreference herein.

Heretofore, heat sealing techniques, even those avoiding contact betweenthe surface being sealed and the bonding apparatus, have not provenentirely successful. Non-contact radiant energy sealing has beenobserved to be generally inconsistent in its ability to thoroughly andsecurely seal balloons to the shafts of catheters along the entireannular extent of the seals. A catheter balloon must have no weak pointsat which the fluid under pressure will slowly dissipate from the balloonwhen in the environment of the body tissue, which can lead to patientdiscomfort and occasionally dislodgement from its intended locationwithin the body of the patient.

The present invention provides a method, a shrink tubing means, and anapparatus for forming the types of seals required to meet these needs.Method steps in accordance with this invention include the use of shrinktubing to hold the balloon in place and simultaneously assist in shapingsmooth seals, which method includes preshrinking the shrink tubing intoplace. Preferably, in close association with this method is a shrinktubing means that has been discovered to be especially useful inconnection with the forming of extremely secure and consistent sealingthroughout the entire annular extent of the radiant energy seal. Theapparatus of the present invention provides a uniform annular band ofradiant energy to be supplied according to the method of this invention,which radiant energy is transmitted through the shrink tubing meansaccording to this invention. In a preferred aspect of the invention,tinted lengths of shrink tubing are placed over the annular locations tobe sealed along the catheter shaft, the shrink tubing is preshrunk alonga predetermined length thereof, and the head end of the catheter is theninserted into the apparatus whereupon it is automatically aligned to theproper location along the shaft, radiant energy is applied, and theapparatus then automatically aligns the shaft to the next locationtherealong, after which further heat sealing treatment is carried out inorder to complete the seal at another location along the shaft.

It is accordingly a general object of the present invention to providean improved method, means, and apparatus for preparing medical deviceshaving overlapping members to be sealed together.

Another object of the present invention is an improved apparatus, meansand method for assembling a cylindrical balloon to a balloon catheter orthe like in a manner that forms a uniform and secure annular seal thatis smoothly tapered for the avoidance of unnecessary trauma to thepatient being treated with the device.

Another object of this invention is an improved method, means andapparatus for forming an annular seal between thermoplastic materials,which seal is extremely secure and smoothly tapered as between acylindrical shaft and an overlying cylindrical balloon.

Another object of the present invention is an apparatus and itsassociated method whereby precise locations along a cylindrical shaftare subjected to an annular ring of radiant energy and automaticallyindexed to the next location.

Another object of the present invention is an improved shrink tubingmeans for forming radiant energy heat seals that are especially secureand well tapered in association with the method of this invention, whichmeans precisely transmits and directs appropriate heat sources in orderto optimize the effectiveness of the heat source in producing anextremely secure and consistent seal.

Another object of the present invention is an improved apparatus, methodand means for producing balloon catheters and the like with minimalassembly operator involvement and in an extremely short length of timeto minimize the amount of heat conducted away to the materialsurrounding the bond zone, leading to less heat distortion and possiblechemical changes in the material.

Other objects of the present invention will be apparent from thefollowing detailed description, taken in conjunction with theaccompanying drawings wherein:

FIG. 1 is a top plan view, partially broken away, of the preferredapparatus according to this invention;

FIG. 2 is a sectional view of the preferred apparatus, generally alongthe line 2--2 of FIG. 1;

FIG. 3 is an elevational view, partially broken away and partially inlongitudinal section, of a Foley catheter made in accordance with thisinvention;

FIG. 4 is an elevational view, partially in longitudinal section, of thehead end of an unfinished cathether having a length of tubing over anunfinished head end, the tubing for forming a catheter balloon sealed tothe shaft;

FIG. 5 is an elevational view, partially in longitudinal section, of theunfinished catheter head end as shown in FIG. 4, with two lengths ofshrink tubing having been slid thereover;

FIG. 6 is an elevational view, partially in longitudinal section, of theunfinished catheter head end of FIGS. 4 and 5, illustrating thepreshrinking step in accordance with this invention;

FIG. 7 is an elevational view, in partial longitudinal section, of thecatheter head shown in FIGS. 4-6, illustrated after completion of theradiant energy seal and prior to removing the shrink tubing andfinishing the tip of the head to form the catheter head end shown inFIG. 3;

FIG. 8 is an elevational view, partially in longitudinal section, of anunfinished catheter head showing a heat seal not in accordance with thisinvention and assembled according to a method not including apreshrinking step; and

FIG. 9 is an elevational view of a finished catheter head made by themethod and means illustrated in FIG. 8, and not according to the presentinvention.

The apparatus illustrated in FIGS. 1 and 2, designated generally by 21,has a case 22, a plurality of sources of radiant energy or lamps 23, aplurality of curved reflectors 24 associated with each lamp 23, a shaftreceiving opening 25, and a shaft depth indexing means, generallydesignated 26. Shown inserted into the opening 25 is the head portion ofan unfinished catheter 27 which, prior to treatment within the apparatus21, is at the stage generally illustrated in FIG. 6. Apparatus 21automatically indexes the unfinished catheter 27 such that the locationsto be sealed with radiant energy will be precisely aligned with acylindrical treatment site 28 at which is developed a concentrated andfocused band of radiant energy emanating from lamps 23 and reflectors24.

A first portion 31 of the unfinished catheter 27 is subjected to theband of radiant energy at the cylindrical treatment site 28. Movement toa second portion 32 of the unfinished catheter 27 is accomplishedthrough the operation of the shaft depth indexing means 26. Moreparticularly, means 26 includes upwardly biased linkage, generallydesignated 33, to urge a top switch 34 upwardly for engagement with astylet 35 inserted into lumens of the unfinished catheter 27. Whenswitch 34 is activated by contact with stylet 35, a timer is activatedfor transmitting radiant energy sealing power to the lamps 23 for apredetermined length of time, after which the timer also activates asolenoid 36 to withdraw an upper stop 37 from its operativeinterengagement with the top switch 34 through an arm 38 and anadjustable pin 39. With upper stop 37 withdrawn it is then possible tofurther insert the unfinished catheter 27 through the shaft receivingopening 25, in opposition to the bias provided by linkage means 33, soas to move arm 38 downwardly until pin 39 engages a lower stop 41, atwhich time the second portion 32 of the unfinished catheter 27 will bealigned with the cylindrical treatment site 28, which alignment can befacilitated by an adjustor screw 40. As the adjustable pin 39 engagesthe lower stop 41, a bottom-switch 42 is closed to operate a timer toagain provide heat sealing energy to the lamps 23 for a predeterminedlength of time.

This completes the heat sealing operation, and the unfinished but sealedcatheter 27 is then withdrawn through the shaft receiving opening 25, atwhich time the top switch 34 will return to its initial position shownin FIG. 2 by the force supplied by a biasing means 43 through thelinkage means 33. Complete withdrawal of the catheter 27 releases thetop switch 34 which results in replacement of the upper stop 37 to itsstop position shown in FIG. 2.

In the preferred embodiment of apparatus 21 as illustrated in FIGS. 1and 2, three lamps 23 are mounted within three reflectors 24 located120° between each other to provide radiant energy that is substantiallyuniform throughout the cylindrical treatment site 28, which even heatingis enhanced by overlapping reflection patterns emanating from thereflectors 24, which patterns include reflected oblique rays, therebyeliminating any need to rotate the catheter 27. Other configurations arepossible, such as having four lamps that are 90° apart from each other,in which case a greater intensity of radiation could be provided forsealing.

Lamps 24 emit energy in the form of visible and infrared light forabsorption at the first portion 31 and the second portion 32 of catheter27. It is preferred, in order to reduce electrical inrush current andheating time variation, that the filaments of the lamps 23 be kept warmon standby at a voltage of about five percent of the rated lamp voltagein between the times that the lamps are provided with full radiantenergy sealing power when activated by contact of the top switch 34 andthe bottom switch 42. Preferably, each lamp has a very small and veryhot filament in order to provide especially accurate focusing of theradiant energy emanating therefrom. A typical acceptable filamentdiameter is on the order of 1/16 inch.

Preferred reflectors 24 are highly polished metal and have a preciseelliptical shape in longitudinal cross section as shown in FIG. 2, witheach lamp 23 being located along foci of the respective ellipses. Theseelliptical surfaces are preferably opposite generally conical secondaryreflector surfaces 44, 45. By this arrangement of the reflectors 24, 44and 45, about two thirds of the radiant energy supplied by the lamps 23is delivered to the other focus of each respective ellipse, these otherfoci being generally located along the cylindrical treatment band orsite 28.

It is usually advantageous to have the apparatus 21 operate atequilibrium conditions, which can be generally achieved through the useof a cooling means by which a liquid, typically water, at approximatelyroom or ambient temperature is cycled through jackets 46 in thereflectors 24. This cooling fluid is passed through each jacket 46 byway of a pump means 47 that is controlled by a thermostat 48. Thepreferred mode of operation of the cooling means includes an initialcalibration run to determine the appropriate sealing temperature to bedeveloped and to set the thermostat 48 accordingly. Then, as thetemperature at thermostat 48 rises above this preset temperature, thethermostat 48 activates pump means 47 to pass the cooling fluid into andthrough jackets 46. When the temperature at thermostat 48 falls belowthe preset temperature, the thermostat 48 will shut off the pump means47, allowing the cooling fluid to stop flowing through jackets 46 andconduit means 51.

The preferred catheter made in accordance with this invention, generallydesignated 61, is shown in FIG. 3. Catheter 61 includes an elongatedshaft 62 having a fluid draining lumen 63 and an inflation lumen 64which are coventional structures for providing a drainage path from thebladder or the like and for inflating the balloon portion 65 forsecuring it therewithin, respectively. More particularly, when catheter61 is inserted into the patient, body fluids leave the patient by way ofa port 66, pass through the fluid drainage lumen 63 and an outletconduit 67 located within a branched connector 68 for passage to anaspirator or other conventional collection means. Branched connector 68also includes a branch 69 having a valve 71 to receive the luer of asyringe (not shown) and to allow the syringe to place pressurized fluidsuch as sterile water or air into the inflation lumen 64 for inflationof the balloon portion 65 by passing through an opening 72 (FIG. 4) inthe wall of the shaft 62 beneath the balloon portion 65. The valve 71 isstructured to retain the fluid pressure after the syringe is withdrawn,the valve being conventional for use on a Foley catheter.

FIG. 4 illustrates an initial step in the preferred catheter balloonassembly method in accordance with this invention. A length ofthin-walled tubing 73 is slid over the elongated shaft 62 so that itoverlies the wall opening 72. The next step is shown in FIG. 5 wherebyone or more lengths of shrink tubing, preferably two lengths of shrinktubing 74, 75 are installed over the thin-walled tubing 73 so as to haveapproximately half of its length overlap the elongated shaft 62. It willbe noted that, because of the difference in diameters between theelongated shaft 62 and the shrink tubing 74, 75, there is a gap betweenthe elongated shaft 62 and each of the lengths of shrink tubing 74, 75.

FIG. 6 illustrates the step of preshrinking the shrink tubing 74, 75,which step is an important feature of this invention. Basically, eachlength of tubing 74, 75 is subjected to an environment including anelevated temperature at which tubing 74, 75 will partially shrink indiameter, which preshrinking temperature is lower than that which willbring about maximum diameter shrinkage. This preshrinking step has amajor objective of removing these gaps between the elongated shaft 62and the shrink tubing 74, 75. Preferably, this is accomplished byselectively preshrinking the lengths of shrink tubing 74, 75 byconcentrating the preshrinking energy at the section of each shrinktubing 74, 75 that overlaps the elongated shaft 62, such selectivepreshrinking typically being concentrated along circumferential bandsillustrated at 76 and 77.

Also shown on FIG. 6 are the first and second portion, 31, 32 of theunfinished catheter 27 which are subjected to radiant energy, preferablyat a cylindrical treatment site 28 of apparatus 21 (FIGS. 1 and 2). Itis to be noted that the stylet 35 provides support for both fluiddrainage lumen 63 and inflation lumen 64 during the preshrinking andradiant energy applying steps so as to prevent collapse or deformationof these two lumens that could be brought about by the elevatedtemperatures associated with each step. During the radiant energyapplying step, the focused energy from lamps 23 strikes first and secondportions 31, 32, whereupon the shrink tubing 74, 75 further shrinks andthe tubing 73 and shaft 62 are subjected to a temperature in theirthermoplastic melting ranges whereby the tubing 73 is softened, shaped,and thermoplastically bonded to the softened shaft 62 into a smooth andgradually tapering thermoplastic joint 78 which has a trailing edge thatis generally flush with the outside surface of the elongated shaft 62 asis illustrated in FIG. 7 and as is illustrated in FIG. 3 after theshrink tubing 74, 75 has been removed.

FIGS. 8 and 9 illustrate the results typically realized when thepreshrinking step is omitted, the illustration being somewhatexaggerated for drawing clarity. In this case, the elongated shafthaving the thin-walled tubing 73 and the lengths of shrink tubing 74, 75located thereon, generally as shown in FIG. 5, is inserted into theapparatus 21 and serially treated in substantially the same manner asthis invention at the first portion 31 and the second portion 32;however, since the lengths of shrink tubing have not been preshrunk,they develop their greatest annular shrinkage in the central portionthereof to have the general configuration of lengths 79, 81, therebycausing the extreme ends of the thin-walled tubing 73 to flow in thedirection of these extreme ends and generally into the gaps between theelongated shaft 62 and the non-preshrunk shrink tubing lengths 79, 81,which brings about formation of annular flanges 82, 83, which areundesirable from the point of view of causing trauma and discomfort tothe patient. Also, when these seals are formed with irregularities suchas the flanges 82, 83, this has generally been found to result in sealsbetween the balloon and the catheter shaft that are not as uniformlyformed or as secure as the gradually tapering joints 78. Joints 78exhibit enhanced mechanical strength and resistance to peel back whichwould result from irregularities where failure of the bond couldinitiate.

With more particular reference to the method of this invention,especially to the means and materials used in practicing the same, thecatheter shaft 62 is extruded of a material that is typically athermoplastic one having a characteristic thermoplastic melting range. Atypical characteristic range is between 350° and 450° F. It is usuallymost convenient that the thin-walled tubing 73 for forming the balloonbe made of substantially the same material as the catheter shaft,although this is not a requirement provided the shaft and balloonmaterials are compatible, will soften in the radiant energy applyingtemperature range, and will form a good thermoplastic bond with eachother.

Materials for the catheter and balloon should be acceptable for usewithin a patient for periods of time between about one day and about oneweek, for which lengths of time the materials should exhibit very lowtoxicity so that little or no irritation is experienced by the patient.These materials should exhibit limited friction with body tissue and asignificantly reduced tendency to collect encrustation by providing asurface that exhibits a high degree of smoothness and gloss. Suitablematerials preferably should have a cost on the order of that of naturalrubber latex while being as non-toxic as silicone rubber. Such materialsshould also be capable of simple extrusion without a postcure time, andshould exhibit a thermoplastic softening temperature high enough topermit autoclaving of the finished catheter if desired. The tubingmaterial should be kink and collapse resistant at typical wallthicknesses so as to withstand aspiration during normal use. Ifpossible, the thin-walled tubing for making the balloon may haveespecially acceptable elastomeric recovery properties and low creepproperties so as to reduce the formation of wrinkles upon deflation ofthe balloon.

When the catheter and balloon unfinished head end is treated by themethod and apparatus of this invention, much of the visible and infraredradiation penetrates the balloon-forming tubing, even though it isusually white pigmented and opaque to visible light, which radiation isabsorbed below the surface so that the sealing or welding interface ishotter than the surface, a feature that promotes excellent bondformation.

The precise materials suitable for use in this regard can be among thosementioned in said co-pending applications, such as oil-filledthermoplastic rubber materials, and those including a composition of athermoplastic rubber block copolymer, a crosslinkable organic siliconeelastomer and a hydrophobic oil-type plasticizer, the plasticizer beingfor imparting softness to the elastomeric composition. Also, a materialsuch as a silicone product that is not thermoplastic could be used inconjunction with the placing of a heat curable adhesive between theshaft and the balloon member, such adhesives being of the type thatexhibit accelerated cure when heated.

The shrink tubing 74, 75, is made of a material that will shrink uponbeing subjected to heat. For use in accordance with this invention, thematerial should exhibit a preshrinking characteristic whereby it willpartially shrink under conditions that will not substantially deform theunderlying substrate and will shrink further when subsequently subjectedto higher temperatures than those characteristic of the partial shrinkor preshrink stage. Also, the shrink tubing material should not developpinholes or melt upon being exposed to the temperatures and conditionsnecessary to heat seal the balloon member to the shaft.

These shrink tubing materials should not adhere to any substantialdegree to the shaft and balloon materials being shaped and bonded.Preferably, such materials will shrink only in a annular manner wherebythey are uniformly reduced throughout the circumference, but they willnot shrink longitudinally which would lead to shrivelling and a deformedbond. A further particularly advantageous feature to be exhibited by theshrink tubing material is having the ability to be tinted.

Materials that have been found to possess substantially all of thesefeatures are fluorinated polyolefin materials, such as fluorinatedethylene propylene (fep) which has a particularly advantageous set oftwo-stage shrinking temperatures, tetrafluoroethylene, which has a setof temperature ranges somewhat higher than fep, and copolymers ofethylene and tetrafluoroethylene, which usually have a set of shrinktemperatures generally lower than fep.

Fep is particularly preferred because it is transparent and hasexcellent release characteristics, because it will not melt untilreaching temperatures above about 450° F. under the conditions of thisinvention, and because it has an initial preshrink temperature of about250° F. and full shrink temperature range between about 350° and 450° F.

Especially advantageous results are achieved when the shrink tubing istinted with a pigment or the like, which has unexpectedly been found toincrease the rate of bond formation and to further enhance theuniformity of the annular shrink properties of such tubing. For example,when comparing the use of untinted fep shrink tubing with the use ofappropriately tinted fep tubing under the same conditions and forbonding the same materials, the preshrinking was completed in a timeperiod about 25% less than the time required for the untinted tubing,and the subsequent sealing time was reduced to even a greater degree,the untinted taking about 1.8 seconds and the tinted tubing taking only1.2 seconds to complete formation of the tapered bond. Additionally, theuntinted material was found to result in balloon-to-shaft bonds that hadsome weak points at spaced locations around the bond.

While we do not wish to be bound by any theory, it is believed that thepigment within the shrink tubing may scatter the radiant energy togenerate additional heat under the shrink tubing. It is additionallybelieved that metal within the pigment might bring about a moreefficient heat transfer, which could be a reason why tinted shrinktubing improves a preshrinking step which uses only a source of hot airto provide the preshrink environment, no radiation energy beingemployed.

The amount of tinting employed should be in a range so that the tint isfaint enough that most of the radiant energy passes through the shrinktubing and is used to directly heat the balloon member and the shaft;yet the amount of tinting must be substantial enough to realize theadvantageous results in accordance with this aspect of the inventionoften indicated by a noticeable slight warming of the shrink tubingitself. If the tinting is too great, too much heat will be developed inthe shrink tubing and swelling of the bond will occur, resulting in adeformed product. Broadly speaking, the tinting range will provide atinted shrink tubing having a characteristic lower tinting limitslightly above transparency and an upper tinting limit approachingtranslucency. The upper limit will be less than that of opacity,typically occurring at a weight percent range of about 0.5 weightpercent of pigment based on the total weight of the shrink tubingcomposition. A usual range within which many pigments develop suitabletinting of fluorinated polyolefin materials is between about 0.01 andabout 0.1 weight percent, based upon the total weight of the shrinktubing. The most advantageous pigment concentration will vary, ofcourse, with the pigment used and with the material being tinted.

When the pigment contains a metal, it preferably should not be a heavymetal in order to reduce any possible toxicity risks. Preferred pigmentsshould exhibit a flat reflectance curve so that low reflectance, on theorder of 1 percent, is generally uniformly observed substantiallythroughout the entire wavelength range, from ultraviolet throughinfrared. A particularly acceptable shrink tubing is a formulation offep with 0.025 weight percent of a black inorganic pigment formed intoshrink tubing having a wall thickness of about 11 thousandths of aninch, which has been employed in this invention and has been found toreduce the preshrinking time by about 25 percent and reduce the bondingtime by about 1/3 when compared with non-tinted fep, while exhibiting ashrink that is more uniform than and a balloon-to-shaft seal that isstronger than that obtained with non-tinted fep.

It will be apparent to those skilled in this art that the presentinvention can be embodied in various forms; accordingly, this inventionis to be construed and limited only by the scope of the appended claims.

We claim:
 1. A method for using radiant energy for sealing annular endsof a tubular member onto an elongated shaft of a medical device,comprising:sliding the tubular member over an unfinished elongated shaftof the medical device; installing a length of tinted shrink tubing tooverlie at least a part of both the shaft and the tubular member to formfirst and second portions that include at least a part of the shrinktubing and of the shaft and tubular member thereunder; preshrinking saidtinted shrink tubing while installed to overlie at least a part of boththe shaft and tubular member; inserting the unfinished shaft includingsaid first and second portions into an enclosure having a cylindricaltreatment site providing a band of radiant energy; and aligning saidfirst and second portions of the unfinished shaft with said band ofradiant energy at the cylindrical treatment site for sealing the annularends of the tubular member to the shaft.
 2. The method of claim 1,further comprising passing a stylet into a lumen of said elongated shaftprior to said inserting step in order to avoid closing the lumen.
 3. Themethod of claim 1, wherein said preshrinking step is a selectivepreshrinking step by concentrating energy for such step only at thesection of shrink tubing that overlaps the elongated shaft and does notsignificantly overlap the installed tubular member.
 4. The method ofclaim 1, wherein said preshrinking step includes substantially closing agap between the shrink tubing and the shaft.
 5. The method of claim 1,wherein said sealing of the annular ends of the tubular member to theshaft includes softening and shaping the tubular member, softening theshaft, and bonding the softened and shaped tubular member to thesoftened shaft.
 6. The method of claim 1, wherein said preshrinking stepis at a temperature between about 200° F. and about 350° F., and whereinsaid sealing is at a temperature of between about 350° F. and about 450°F.
 7. The method of claim 1, wherein the band of radiant energypenetrates to a bonding interface between the tubular member and theelongated shaft.
 8. The method of claim 1, further comprising providingshrink tubing that shrinks substantially only in an annular manner to beuniformly reduced throughout its circumference.
 9. The method of claim1, further comprising providing shrink tubing of a fluorinatedpolyolefin material.
 10. The method of claim 1, wherein said tintedshrink tubing increases the rate of sealing and enhances the strengthand consistency of sealing.
 11. The method of claim 1, wherein saidtinted shrink tubing is tinted by incorporating an amount of pigmentthereinto, said amount providing a tinted shrink tubing having acharacteristic lower tinting limit slightly above transparency and anupper tinting limit approaching translucency.
 12. The method of claim 1,wherein said sliding step and said sealing step are carried out with atubular member that is thin-walled.
 13. The method of claim 1, furthercomprising placing a heat curable adhesive between the shaft and thetubular member.
 14. The method of claim 1, further comprising removingthe shrink tubing from the shaft after the sealing step.
 15. A method ofsealing annular ends of a tubular member onto an elongated shaft of amedical device comprising the steps of:sliding the tubular member overan unfinished elongated shaft of the medical device; installing twolengths of tinted shrink tubing, one length at each end of said tubularmember to overlie a part of both the shaft and the tubular member toform first and second portions that include at least a part of theshrink tubing and of the shaft and tubular member thereunder;preshrinking said tinted shrink tubing while it is installed to overliepart of both the shaft and the tubular member; inserting the unfinishedshaft including said portions into an enclosure having a cylindricaltreatment site capable of providing a band of radiant energy; aligningsaid first and second portions of the unfinished shaft at a location insaid cylindrical treatment site for sealing the annular ends of thetubular member to the shaft with said band of radiant energy; andapplying said radiant energy at said first and second portions therebysealing the annular ends of said tubular member onto the shaft.
 16. Themethod of claim 15, wherein the step of sliding said tubular member oversaid shaft further includes the step of providing said tubular memberand said shaft comprised of a material from the group consisting ofoil-filled thermoplastic rubbers, and those including a composition of athermoplastic rubber block copolymer, a crosslinkable organic siliconeelastomer and a hydrophobic oil-type plasticizer.
 17. The method ofclaim 15, wherein the step of installing shrink tubing further includesthe step of providing shrink tubing comprising a fluorinated polyolefinincluding a pigment.
 18. The method of claim 15, further including thestep of placing a heat curable adhesive between the shaft and thetubular member.
 19. The method of claim 15, further including the stepof removing the shrink tubing from the shaft after the sealing step.